As the rumored October launch date of the iPad mini inches closer, evidence of the tablet’s existence is starting to pick up. We’ve seen rear shells, dock connectors and even cases that reportedly belong to the device.

And today, it looks like even more proof has surfaced. An iOS developer is reporting that he has spotted two new iPad devices in his app logs, which he believes could be variations of Apple’s highly-anticpated new tablet…

Marco Arment, the developer behind the popular Instapaper app, says he has recently noticed two new iPad device models in his app logs: iPad2,5 and iPad2,6. And while these could easily be the retooled third-gen iPad we keep hearing about, or even a revamped iPad 2, it seems more likely that they are, in fact, the new iPad mini:

“The much more likely explanation is that iPad2,5 and iPad2,6 are the new “iPad Mini” in Wi-Fi and GSM, and I haven’t recorded the likely iPad2,7 CDMA version yet.

If so, this suggests that the iPad Mini is, effectively, an iPad 2: an A5 with 512 MB of RAM and enough GPU power to drive the Gruber Display, but not a Retina Display.

It’s a textbook Tim Cook supply-chain move: selling the last generation’s hardware at a lower price point to expand marketshare.”

For those who missed it, the “Gruber Display” is a reference to Apple pundit John Gruber’s speculation that the iPad mini would house the same 1024 x 768 display found in the original iPad, just cut smaller. Which makes sense.

It’s also worth noting that Arment says that device models could be faked by “a jailbreaker with enough free time.” But he goes on to say that he’s never had a device show up in his logs that didn’t end up being a real, upcoming Apple device.

Apple is expected to unveil a new, smaller iPad this October with a 7.85-inch display and a price tag well under the $300 mark.